Ground-state cooling enabled by critical coupling and dark entangled states

Cortes, Cristian L.; Otten, Matthew; Gray, Stephen K.

doi:10.1103/physrevb.99.014107

Cited by 8 publications

(7 citation statements)

References 45 publications

(71 reference statements)

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“…the system of two non-resonantly coupled oscillators). Since the effective non-resonantly coupled oscillators did not turn out to interact with each other, and second order constant frequency shifts (7) can be included in the renormalized frequencies of oscillators с  and r  ,…”

Section: The Transformation Generators Determine Not Only the Second mentioning

confidence: 99%

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Theory of relaxation and pumping of quantum oscillator non-resonantly coupled with the other oscillator

Trubilko

Башаров

2020

Phys. Scr.

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The paper shows mechanisms of both the pumping and energy decay of an "isolated" oscillator. The oscillator is only non-resonantly coupled with the adjacent oscillator which resonantly interacts with the thermal bath environment. Under these conditions the "isolated" oscillator begins interacting with the thermal bath environment of the adjacent oscillator. The conclusion is based on the kinetic equation derived relative to anti-rotating terms of the initial Hamiltonian, with the latter being the Hamiltonian of two oscillators and environment of one of them.Quantum oscillators simulate photon systems in micro resonators, which can be either coupled with each other on mirrors or with pump and vacuum (thermal bath) fields of the thermal bath, providing an example of an open quantum system. Interaction with thermal baths leads to the attenuation of quantum oscillators. Effective research of attenuating quantum systems were made possible due to the introduction of the notion of a kinetic equation (master equation) into the mathematical apparatus of nonlinear and quantum optics [1][2][3].In [4][5], the general form of the kinetic equation is established, that is now commonly referred to as the Lindblad-type of the kinetic equation. Many recently published papers on the analysis of open quantum systems dynamics start with the definition (as initial ones) of precisely kinetic equations in the Lindblad form with a predefined Lindblad operators.In view of this, researchers consider atomic systems interacting with electromagnetic fields of various nature [6-9], photon systems consisting of photons of cavity modes interacting with other cavity systems, with intracavity and boundary atoms [10][11][12][13], and other optical problems.Since the relaxation channels are already defined by the appropriate terms and Lindblad operators in the initial equations, the majority of further approximations, and, in particular, dispersion approximation do not adequately describe the case under study. In fact, in optics, the initial Hamiltonian of two non-resonantly interacting atoms has both rapidly and slowly varying terms. This is distinctly seen from the Hamiltonians of the basic models of quantum optics in the interaction representation [14,15]. The rapidly varying terms in the interaction representation are commonly referred to as anti-rotating ones. It was observed that in optical problems the success of the approach based on kinetic equations in the Lindblad form is due to the neglect of antirotating terms [16]. However, the neglect is possible only in resonant processes, and not always in all cases [17,18]. Thus it is vital to take into account the anti-rotating terms in deriving the kinetic equation for resonant, quasi-resonant and non-resonant processes, as well as to analyze their significance in optical effects.The present paper considers the dynamics of a quantum oscillator that is non-resonantly coupled to another oscillator. The connection of the kind is often neglected, assuming that the given oscillator can be considered t...

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Section: The Transformation Generators Determine Not Only the Second mentioning

confidence: 99%

“…In view of this, researchers consider atomic systems interacting with electromagnetic fields of various nature [6][7][8][9], photon systems consisting of photons of cavity modes interacting with other cavity systems, with intracavity and boundary atoms [10][11][12][13], and other optical problems.…”

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confidence: 99%

Theory of relaxation and pumping of quantum oscillator non-resonantly coupled with the other oscillator

Trubilko

Башаров

2020

Phys. Scr.

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“…Ground-state cooling enabled by critical coupling and dark entangled states was found in [32]. Further interesting works on cooling or entanglement processes are presented in Refs.…”

Section: Introductionmentioning

confidence: 95%

Entanglement versus cooling in the system of a driven pair of two-level qubits longitudinally coupled with a boson-mode field

Cecoi

Ciornea

Исар

et al. 2020

J. Phys. B: At. Mol. Opt. Phys.

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The relationship among the entanglement creation within coherently pumped and closely spaced two-level emitters longitudinally coupled with a single-mode boson field, and the subsequent quantum cooling of the boson mode is investigated. Even though the two-level qubits are resonantly driven, we have demonstrated an efficient cooling mechanism well below limits imposed by the thermal background. Furthermore, the cooling effect is accompanied by entanglement of the qubit pair components when the dipole-dipole frequency shift is close to the frequency of the boson mode.The maximum boson mode cooling efficiency realizes on the expense of the entanglement creation.Importantly, this occurs for rather weak external pumping fields protecting the sample from the deteriorations. Finally, the conditions to effectively optimize these effects are described as well. * Electronic address: macovei@phys.asm.md Entanglement in a few-atom system attracted enormous attention over last few decades [1][2][3][4][5][6][7][8]. Small qubit samples may form buildings blocks for even larger networks with huge potential applications for quantum technologies [9][10][11][12][13][14][15][16][17][18][19]. Generally, a thorough description of the entanglement creation in a two-atom system was given in [20]. From this point of view artificial atomic systems have been widely investigated as well. Particularly, experimental realization of entanglement in two coupled charge qubits was performed in [21]. Entanglement of two quantum dots inside a cavity injected with squeezed vacuum was predicted as well, in [22]. Ultra-strong dipole-dipole interacting two-level superconducting flux qubits are naturally entangled through their corresponding environmental reservoir and maximum coherence can be induced too [23]. Furthermore, a pair of moderately dipole-dipole coupled and laser pumped two-level quantum dots get maximal entangled via their environmental phonon thermostat which facilitates also the creation of a subradiant two-qubit state [24].Recently, based on quantum dots systems, a relevant experimental realization of an interconnection among two qubits located five meters apart from each other, via single photons, was reported in Ref. [25].Often to realize quantum states of matter or light one requires ground-state cooled individual or coupled quantum systems, respectively. In this context, cooling of a quantum circuit via coupling to an independent or Dicke-like interacting multiqubit ensemble was demonstrated in [26]. The cooling of a nanomechanical resonator coupled to two interacting flux qubits via the corresponding subradiant Dicke states was demonstrated as well, in Ref. [27]. A scheme for ground-state cooling of a mechanical resonator coupled to two coupled quantum dots forming an effective Λ-type three-level structure was presented in [28].

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“…Somewhat more interesting behavior occurs when one uses the parameters of Ref. [18], which are designed to be consistent with a more complex plasmonic structure that exhibits gap plasmons. Employing these parameters (also listed in Table I), and now with no driving (EL = 0) but setting the initial condition to be one of the quantum dots is in its excited state, we obtain the results in Figs.…”

Section: B Coherences and Entanglementmentioning

confidence: 99%

Non-Hermitian approach for quantum plasmonics

Cortes

Otten

Gray

2020

The Journal of Chemical Physics

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We examine the limits of applicability of a simple non-Hermitian model for exciton/plasmon interactions in the presence of dissipation and dephasing. The model can be used as an alternative to the more complete Lindblad density matrix approach and is computationally and conceptually simpler. We find that optical spectra in the linear regime can be adequately described by this approach. The model can fail, however, under continuous optical driving in some circumstances.In the case of two quantum dots or excitons interacting with a plasmon, the model can also describe coherences and entanglement qualitatively when both dissipation and dephasing are present, and quantitatively in the limit with no dephasing. The model can also be extended to the case of many quantum dots interacting with a plasmon and results, within the single-excitation manifold, are presented for the fifty quantum dot case.

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Ground-state cooling enabled by critical coupling and dark entangled states

Cited by 8 publications

References 45 publications

Theory of relaxation and pumping of quantum oscillator non-resonantly coupled with the other oscillator

Theory of relaxation and pumping of quantum oscillator non-resonantly coupled with the other oscillator

Entanglement versus cooling in the system of a driven pair of two-level qubits longitudinally coupled with a boson-mode field

Non-Hermitian approach for quantum plasmonics

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